Murphy MC-900 Series - Manual (Page 3)

Section 1: Introduction
1-1 System.
1-1.1
The MURPHYMATIC ® Manual Generator Engine
Control System, Series MC-900 is designed to meet the
requirements of the engine control and shutdown for manual
start generator engines.
By combining one of the MC-900 series controls with generator
instruments, a complete engine generator control panel can be
provided.
1-2 Models.
1-2.1 The Series MC-900 is available in two basic
configurations:
1-2.1.1 Model MC-900 for manual start and stop generator sets
with four cycle engines which includes the minimum normal
shutdowns.
1-2.1.2 Model MC-900-2 for manual start and stop generator
sets with two cycle engines which includes the minimum normal
shutdowns and an “Overspeed Relay” to operate the air shutoff
solenoid for overspeed shutdown.
1-2.2 Both models are available for 12 or 24 volt operation.
1-2.3 Both models include four unlabeled shutdown circuits for
additional customer specified shutdowns.
1-2.4 Each model is made up of two parts, a Control/Display
module and a Relay module.
1-3 Purpose.
1-3.1 This manual is directed to the installation, maintenance
and operating personnel who will be in day to day contact with
the MC-900 system.
1-3.2 No manual can cover all aspects of a product. However
the basic knowledge gained with this material will allow those
personnel to easily adjust to special circumstances.
1-4 Definitions.
1-4.1 Throughout this manual, reference is made to
organizations, trade names and trademarks which may not be
familiar to the reader. Some of these are:
1-4.1.1 NFPA: National Fire Protection Association.
1-4.1.2 NFPA-70: The National Electrical Code.
1-4.1.3 Several terms used in this manual are registered
trademarks of Frank W. Murphy Mfr.
(a) MURPHYMATIC ® : Refers to all Murphy automatic
controls.
(b) SELECTRONIC ® : A name that is applied to all electronic
controls manufactured by Murphy.
(c) SWICHGAGE ® : A combination indicating gauge and
switch.
(d) TATTLETALE ® : A term that refers to a shutdown
indicating device or circuit in the control panel.
1-5 How to use this manual.
1-5.1 Section 1, 2, 4, 5, 6 and 7 contain general information that
applies to all MC-900 models.
1-5.2 Section 3, Model Identification, is broken into three sub
sections. Section 3-1 allows you to chose the model that best
fits your requirements and Section 3-2 and 3-3 explain each
models features in detail.
Section 2: Specifications
2-1 Enclosure Type.
2-1.1 The MC-900 Series enclosure is designed to be mounted
in a standard electrical enclosure for indoor use.
2-1.2 The MC-900 Series shares the same enclosure as the A-
900 automatic start controller so they can be used
interchangeably in a generator control panel.
2-2 Power Requirements.
2-2.1 The engine controls, shutdown circuits and shut-down
indicators are powered from the engine starting battery. The
MC-900 series is available in either 12 or 24 volt, negative
ground.
2-2.2 The MC-900 is fused for 3 amp. maximum current.
2-3 Input Ratings.
2-3.1 All input switches should be dry contact type, maximum
current is 2 ma, 8 VDC or less.
2-3.2 Frequency signal for the speed sensing circuit requires a
minimum input of 2 volts RMS from a magnetic pickup
(preferred) or from the tachometer terminal of the battery
charging alternator.
2-3.2.1 Frequency range of the speed sensing circuit is 300 Hz
to 10,000 Hz.
2-4 Output Ratings.
2-4.1 The MC-900 Control / Display Module has outputs for
remote indication of shutdowns. These outputs are transistors
that close to the negative supply (sink) and are rated at 1 amp,
30 VDC maximum.
2-4.2 The Control / Display Module also has an output for an
auxiliary starter contactor which is rated 1 amp, 30 VDC
maximum. This is a transistor that closes to the positive supply
(source).
2-4.3 The Relay Module includes 3 engine control relays with
contact ratings of 7 amp, 30 VDC inductive. These powered
contacts must be suppied from an 8 amp. fuse or circuit breaker
(customer supplied).
2-5 Field Wiring Connections.
2-5.1 All field wiring connections are barrier terminal blocks,
UL rated for 15 amp, 300 volt.
2-6 Operating Temperature.
2-6.1 The operating temperature range of the MC-900 is -4°F to
158°F / -20°C to 70°C.
Section 3: Model Identification
3-1 Model Numbers.
3-1.1 MC-900-12 and MC-900-24: These models are designed
for a manual start four cycle engine driven generator, and
include the minimum shutdown points normally supplied on
such installations. The suffix numbers -12 and -24 indicate the
engine starting battery voltage.
3-1.2 MC-900-2-12 and MC-900-2-24: These models are
designed for a manual start two cycle engine driven generator,
and include the minimum shutdown points normally supplied on
such installations. The suffix numbers -12 and -24 indicate the
engine starting battery voltage.
3-1.2.1 The MC-900-2 series control includes an “Overspeed
Relay” to trip the air shut-off solenoid on overspeed of a two
cycle engine.
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